The Alpha RV Jack Block features a patented stabilizer plate which is designed to keep your RV foot pads level on any surface you find on and off the road. Magnetic Connectors have also been integrated to ensure a solid and flush connection to your pads along with lipped edges to prevent slippage. The Alpha RV block can be dual stacked to reach a wide variety of ground clearances. This Block is Rated at 11,000lbs alone and 6,000lbs when dual stacked. A recessed center also allows for the use of standard trailer jack poles.